Shimano's Deore XT Crankset boasts race-worthy efficiency. Shimano incorporates the crankarms and the bottom bracket spindle into a single unit so you shave grams without losing a drop of valuable pedal power. This design also sports external bottom bracket bearings that increase rigidity and durability. And, the carbon/steel composite middle ring adds rigidity for better shifting, increased service life, and smooth, flex-free power delivery.